I thought it would be good to have a thread discussing strategic resources in Civ 6, as well as just a place to post complete info about which units require strategic resources.
So first of all here are the units that require strategic resources, listed by era:
---- (Ancient) ---
(None)
---- (Classical) ---
Horseman - Horses (Light Cavalry)
Swordsman - Iron (Melee)
---- (Medieval) ---
Knight - Iron (Heavy Cavalry)
---- (Renaissance) ---
Musketman - Niter (Melee)
Bombard - Niter (Siege)
---- (Industrial) ---
Cavalry - Horses (Light Cavalry)
Ironclad - Coal (Naval Melee)
--- (Modern) ---
Battleship - Coal (Naval Ranged)
Tank - Oil (Heavy Cavalry)
--- (Atomic) ---
Fighter - Aluminum (Air Fighter)
Bomber - Aluminum (Air Bomber)
Aircraft Carrier - Oil (Naval Carrier)
Nuclear Device - Uranium (Nuclear Weapon)
--- (Information) ---
Nuclear Submarine - Uranium (Naval Raider)
Jet Fighter - Aluminum (Air Fighter)
Modern Armor - Uranium (Heavy Cavalry)
Jet Bomber - Aluminum (Air Bomber)
Thermonuclear Device - Uranium (Nuclear Weapon)
As we can see, most strategic resources are required for exactly two units; sometimes these two units occur in the same era, such as for Niter, and sometimes these units occur in eras that are quite far apart, as in the case of Horses. The late-game resources of Aluminum and Uranium are used for four units each. In the case of Aluminum, this is require for all air units beyond the Biplane, and is only required by air units. Whereas Uranium is a very interesting late-game resource: it's required, of course, for nuclear weapons, but also for the Modern Armor (upgrade to tank) and the Nuclear Submarine.
Finally, a refresher on how strategic resources work in Civ 6 (subject to my mistaken memory). First note that strategic resources are *only* required for military units, not buildings. So if you're being peaceful, you might be able to eschew strategic resources entirely. Second, you only ever need at most two copies of a strategic resource to build a unit. More specifically, with no other districts you need two copies of a given strategic resources to build a unit that requires it some city; but if you have the relevant district in the city (Encampment for land units, Harbor for naval units, Aerodrome for air units) then you only need one of that strategic.
So first of all here are the units that require strategic resources, listed by era:
---- (Ancient) ---
(None)
---- (Classical) ---
Horseman - Horses (Light Cavalry)
Swordsman - Iron (Melee)
---- (Medieval) ---
Knight - Iron (Heavy Cavalry)
---- (Renaissance) ---
Musketman - Niter (Melee)
Bombard - Niter (Siege)
---- (Industrial) ---
Cavalry - Horses (Light Cavalry)
Ironclad - Coal (Naval Melee)
--- (Modern) ---
Battleship - Coal (Naval Ranged)
Tank - Oil (Heavy Cavalry)
--- (Atomic) ---
Fighter - Aluminum (Air Fighter)
Bomber - Aluminum (Air Bomber)
Aircraft Carrier - Oil (Naval Carrier)
Nuclear Device - Uranium (Nuclear Weapon)
--- (Information) ---
Nuclear Submarine - Uranium (Naval Raider)
Jet Fighter - Aluminum (Air Fighter)
Modern Armor - Uranium (Heavy Cavalry)
Jet Bomber - Aluminum (Air Bomber)
Thermonuclear Device - Uranium (Nuclear Weapon)
As we can see, most strategic resources are required for exactly two units; sometimes these two units occur in the same era, such as for Niter, and sometimes these units occur in eras that are quite far apart, as in the case of Horses. The late-game resources of Aluminum and Uranium are used for four units each. In the case of Aluminum, this is require for all air units beyond the Biplane, and is only required by air units. Whereas Uranium is a very interesting late-game resource: it's required, of course, for nuclear weapons, but also for the Modern Armor (upgrade to tank) and the Nuclear Submarine.
Finally, a refresher on how strategic resources work in Civ 6 (subject to my mistaken memory). First note that strategic resources are *only* required for military units, not buildings. So if you're being peaceful, you might be able to eschew strategic resources entirely. Second, you only ever need at most two copies of a strategic resource to build a unit. More specifically, with no other districts you need two copies of a given strategic resources to build a unit that requires it some city; but if you have the relevant district in the city (Encampment for land units, Harbor for naval units, Aerodrome for air units) then you only need one of that strategic.